This is a common problem brought on by, for one, the sunflower stem borer, aka the soybean stem borer. There is also a weevil. And maybe a couple more. Here is some advice about these various pests, as there is no easy answer/solution: • https://extension.sdstate.edu/dectes-stem-borer-adults-active-sunflower • https://extension.colostate.edu/topic-areas/insects/sunflower-stem-weevil-management-5-585/ We hope this helps. Reply
This is a common problem brought on by, for one, the sunflower stem borer, aka the soybean stem borer. There is also a weevil. And maybe a couple more.
Here is some advice about these various pests, as there is no easy answer/solution:
• https://extension.sdstate.edu/dectes-stem-borer-adults-active-sunflower
• https://extension.colostate.edu/topic-areas/insects/sunflower-stem-weevil-management-5-585/
We hope this helps.